Endowment effect in chimpanzees can be turned on and off

In humans, the endowment effect causes people to consider an item they have just come to possess as higher in value than the maximum price they would have paid to acquire it just a moment before. Economists and lawyers typically assume this will not be the case. And some consider the endowment effect a human-centered fluke, subject to widespread and seemingly unpredictable variation. The origins of the quirk, and satisfying explanations for how it varies, have proved elusive.